An Er:YAG laser (Erbium-doped yttrium aluminium garnet laser, Erbium YAG laser) is a solid-state laser whose active laser medium is erbium -doped yttrium aluminium garnet (Er:Y3Al5O12). Er:YAG lasers typically emit light with a wavelength of 2940 nm , which is infrared light. Applications. Unlike Nd:YAG lasers , the output of an Er:YAG laser is strongly absorbed by water. This fact limits the use of this laser in surgery, and in many other laser applications where water is present. Because of this limitation, Er:YAG lasers are far less common than their relatives such as Nd:YAG and Er:glass lasers. The 2,940-nm wavelength emitted by the Er:YAG laser is absorbed 12-18 times more efficiently by superficial (water-containing) cutaneous tissue than is the 10,600 nm wavelength of the carbon dioxide laser. With a pulse duration of 250 microseconds, a typical short-pulse Er:YAG laser ablates 5-20 µm of tissue per laser pass at a fluence of 5 J/cm2 with minimal residual thermal damage (compared with 20-60 µm of tissue ablation and up to 150 µm of residual thermal damage per pass with the carbon dioxide laser).The Er:YAG emits a wavelength of 2940 nm, which is absorbed by water because of its 3000-nm absorption peak. The passes of short-pulse lasers (250 µm) penetrate to a depth of only 10-15 µm, and several passes only cause collateral thermal necrosis to a distance as thin as 20-50 µm.